Heat exchange apparatus



R. K. MILLER HEAT EXCHANGE APPARATUS June 2, 1942.

Filed July 24, 1940 Fig. 1

2 Sheets-Sheet l ATTORT June 2, 1942. R. K. MILLER HEAT EXCHANGEAPPARATUS Filed July 24, 1940 2 Sheets-Sheet 2 ATTORNEYS Patented June2, 1942 UNITED STATES PATENT OFFICE HEAT EXCHANGE APPARATUS Ralph K.Miller, Dayton, Ohio, assignor to General Motors Corporatiom'Day'ton,Ohio, a corporation of Delaware Application July 24, 1940 Serial No.347,341 4 Claims. (Cl. 257-241)- This invention relates to refrigeratingapparatus and more particularly to means for controlling the contactbetween primaryand secondary heat transfer systems.

Recently there has been introduced a type of refrigerator known as aCold Wall refrigerator. This type differs from conventional householdFig. 4 is asectional view taken along the lines 4 -4 of Fig.2.}

refrigerators in that a glass partition is provided I for dividing theinterior into upper and lower compartments. This type also differs inthat a secondary refrigerant circuit is wrapped around the walls of thelower compartment and has a portion in contact with the evaporator orfreezer -coil in the upper compartment. The temperature of the lowercompartment depends upon this contact between the secondary circuit andthe freezer coil. It is diflicult to make the contact between the baretubing of the secondary circuit with the freezer coil uniform inproduction and considerable servicing is required in'correcting thecontact variations.

It is an object of my invention to provide a contact arrangement betweenthe primary and secondary and heat transfer means which will be uniformwhen made by satisfactory mass production methods.

It is another object of my invention to provide a contact arrangementbetween the primary and secondary heat transfer means which willmaintain desired secondary temperatures.

It is another object of my invention to provide a contact arrangementdesigned to take advantage of certain properties of power tools used inassembling, to obtain uniformity of contact.

It is another object of my invention to provide a contactarrangement'whereby each portion of the contact area' is assured ofproper contact pressure.

It is still another object of my invention to provide a contactarrangement wherein uniform contact area is assured regardless of theconditions of assembly.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Fig. 1 is a perspective view of a refrigerator embodying one form of myinvention;

Fig. 2 is a side view of the primary evaporator or freezer coil with thecontact portion of the secondary circuit mounted thereon; I

Fig. 3 is a view of the opposite side of the contact portion of asecondary circuit; and

While Iha've shown the invention as applied to a household refrigerator,it is applicable to' any contact arrangement between a primary unit anda secondary circuit. The drawings show a Cold Wall type of refrigeratorin which the contact portion of the secondary is formed. into a hairpinloop provided with a contact plate having .webs extending across theloop and provided with contact surfaces held in contact with variouswall'portions of the primary evaporator by screws located at the centerportion of each web.

ticularly to Fig. 1, there is shown a refrigerator cabinet provided withouter metal walls 22 surrounding a box-shaped inner liner member 24.

The space between the inner liner 24 and the outer metal walls 22 isfilled with a suitable insulating material to obstruct the flow of heatinto the interior of the inner liner. Beneath the bottom of the innerliner 24 is a machine compartment containing a refrigerant liquefyingmeans which-supplies liquid refrigerant to and withdraws evaporatedrefrigerant from the primary evaporator 26 located in the upper portionof the interior of the inner liner member 24.

This evaporation within the primary evaporator member 30 may be providedwith ventilating apertures 38, if desired, in order to provide acontrolled amount of ventilation or circulation between the twocompartments.

The lower compartment 36 is cooled by a sec-' ondary refrigerant circuitwhich includes an initial portion 40 fastened to the bottom wall of theinner liner member 24 and a succeeding portion 42 which is wrappedaround and is clamped to the side and rear walls of the inner liner 24beneath the glass dividing partition 30. These portions of the secondarycircuit are connected to a hairpin loop contact portion 44 locatedadjacent a side wall of the primary evaporator 26. This loop enters theupper compartment 34 Referring now to the drawings and more parthrough aslot in the rear wall of the inner liner 24 which is covered by a rubbergrommet 4B or some other suitable covering and sealing means.

evaporator to the secondary circuit varied considerably in differentrefrigerators. This is quite reasonable since different workmen indifferent shifts perform the fastening operation and will not fasten thesecondary tubing to the primary evaporator with the same tightness.Because of this, much servicing was required in order to adjust the.thermal contact between the primary and secondary circuits.

In the construction shown in this application these variations areavoided. Instead of applying the bare tubing directly to the walls ofthe primary evaporator I provide a contact plate 48 which has its upperand lower edges soldered, welded or otherwise bonded to the upper andlower portions of the hairpin loop contact portion 44 of the secondarycircuit. The contact plate 48 is provided with uniformly spaced slots 50throughout its length so as to divide the midportion of the plate intoeight webs 52 which are uniform in width, thickness and shape. The plateis bent into the shape shown most clearly in Fig. 4 so that each web hasa central bowed portion 54 provided with a central aperture whichreceives a fastening screw 56 for clamping its web into contact with theflat portions 58' -The slots 58 receive the refrigerantpassages 50 andthus by this construction no difference need-be made in the constructionof the primary evaporator 26 from the conventional construction. Allthat needs to be done is to provide threaded apertures in the flatportions of'one of the side walls.

The ends of the bowed portion 54 of each web are bent upwardly toprovide convex surfaces 64 and B6 in contact with the wall portion 58 ofthe primary evaporator 26. Preferably this bend is uniform so that nomatter how tight the fastening screws 56 are tightened, the same amountof contact surface is provided. This construction provides line contactbetween the convex portion of each web and the primary evaporator 26 sothat the contact therein is very limited and accurately controlled. Thehairpin loop proper of the secondary circuit is kept away from the primary evaporator 26 and all thermal conduction must pass through thecontactplate 48 which controls the thermal contact between the tworefriger'ant circuits.

The fastening is done by a power screw-driver and the workmen areordered to thread these screws in place with the power screw-driveruntil the motor stalls. Since this stalling point will be uniform, auniform contact pressure between the contact plate 48 and the evaporator26 will be obtained. The bowed portion of each web will serve as a sortof spring to always maintain this contact pressure. Thus by thisconstruction I take advantage of the uniformity of power in the powerscrew-driver machine used in order to secure uniformity with respect tothe contact between the primary and secondary circuits with respect tothe entire output.

The number of webs and slots are varied in accordance with the differentsizes of refrigerators, to satisfy the refrigerating requirements forthe lower compartment.

The primary evaporator 26 is placed close to the wall of the inner liner24 nearest the contact portion 44 so as to reduce the air coolingrequirements of that wall of the primary evaporator and to increase theair flow wiping the bottom and the other side of the primary evaporatorfor cooling the upper compartment.

While the form'of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to be, understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. Heat transfer apparatus including a primary heat transfer unit, meansforming a secondary circuit unit, one of said units being provided withseparated bowed webs having convex surfaces at each end of the bowedportion, and separate fastening means at each 'of said bowed portionsfor holding said convex surfaces firmly in contact with the other unit.

2. Heat transfer apparatus including a pri- 'mary heat transfer unit,means forming a secondary circuit unit, one of said units being providedwith separated web portions, and clamping means for holding each of saidweb portions firmly in contact with the other unit.

.3. Heat transfer apparatus including a primary heat'transfer unit,means forming a secondary circuit unit removably associated with saidprimary unit, said secondary unit being provided with separated webportions, and detachable clamping means for holding each of said webportions firmly in contact with said primary unit.

4. Heat transfer apparatus including a primary heat transfer unit, meansforming a secondary circuit unit, one of said units being provided withseparated bowed webs, and separate clamping means for detachably holdingthe ends of said bowed webs firmly in contact with the other unit.

' RALPH K. MILLER.

